A variety of types of switching regulators are known. Each type of switching regulator achieves a regulated output voltage, which is lower than an input voltage in some circuit arrangements, nearly the same as the input voltage in some other circuit arrangements, and which is higher than the input voltage in some other circuit arrangements.
A so-called buck converter achieves a regulated output voltage, which is lower than an input voltage. One conventional form of buck converter uses one transistor switch in combination with one diode to provide a rectified signal to an inductor and capacitor. Another conventional form of buck converter, sometimes referred to a synchronous buck converter, uses two series connected transistor switches operating generally in opposition, wherein one switch is closed when the other is open and vice versa in order to provide the rectified signal.
A so-called buck-boost converter achieves a regulated output voltage, which is nearly the same as the input voltage. A conventional form of buck-boost converter, sometimes referred to a synchronous buck-boost converter, like the synchronous buck converter, also uses two series connected transistor switches, a first pair of switches, operating generally in opposition, wherein one switch is closed when the other is open and vice versa. The synchronous buck-boost converter also includes a second pair of two series connected switches.
In some applications, in particular automotive applications, the synchronous buck converter and the synchronous buck-boost converter must be designed to withstand a large overvoltage at their input. In automotive applications, this overvoltage may be largest upon a so-called “load dump.” A load dump will be understood to be a condition that occurs at a time when an automobile engine is running, therefore an associated alternator is generating electricity in-part to charge an automobile battery coupled to the automobile power system, and the battery is suddenly disconnected. While the automobile battery is nominally a twelve volt battery, at the time of a load dump, the voltage experience by electronics connected to the automobile power system can be in excess of sixty volts.
It is known that, in order to achieve electronic components, for example, transistors, which are capable of withstanding higher voltages, the electronic components can be made larger. However, it is also known that larger electronic components are generally undesirable.
In the case of power transistors, as may be used as the series connected transistors in the above-described synchronous switching regulators, larger transistors use a larger amount of silicon area in an integrated circuit. Larger silicon area tends to result in lower integrated circuit yield during manufacture, a lower quantity of integrated circuits available on a silicon wafer during manufacture, and therefore, a higher integrated circuit cost.